The infection of Escherichia coli with T-even and T-odd bacteriophages results in specific alterations of the translational machinery, one of these is the induction of phage-specific tRNAs. The function of these phage tRNAs in the viral replicative process is not clear. The specific aim of this proposal is to gain further information about the newly induced bacteriophage tRNAs, mainly, their synthesis and role in phage protein synthesis. We have physically defined four separate loci in the T5 genome which code for some 16 different tRNA species. One of our goals is to refine the T5 tDNA map so that the precise order of the tRNA genes will be known. Many of the tRNAs show multiple isoacceptor species when subjected to reversed-phase chromatography, hence it is important to determine whether these isoacceptor tRNAs are coded from single or multiple gene sites. It is now possible to isolate a T5 DNA fragment containing all of the tRNA genes. We expect to use this fragment for in vitro transcriptional studies to gain insight into the regulation of phage tRNA synthesis. BIBLIOGRAPHIC REFERENCES: Hunt, C., Hwang, L-T., and Weiss, S.B., Mapping of Two Isoleucine tRNA Isoacceptor Genes in Bacteriophage T5 DNA. J. Virol. 20, 63-69, 1976. Hunt, C., Locker, J., and Hwang, L-T., and Weiss, S.B., The Detection of Two T5 Isoleucine tRNA Genes and their Approximate Map Position in T5 DNA. Fed. Proc. 35, 1976.